Prenatal Allospecific NK Cell Tolerance Hinges on Instructive Allorecognition through the Activating Receptor during...

Area of Science:

• Immunology
• Developmental Biology
• Transplantation Immunology

Background:

• The prenatal development of natural killer (NK) cell tolerance to alloantigens is poorly understood.
• The role of corecognition by shared specificity activating and inhibitory receptors in NK cell education is uncharacterized.

Purpose of the Study:

• To investigate how conflicting signals from alloantigens via activating and inhibitory receptors influence NK cell repertoire formation and licensing during prenatal development.
• To elucidate the mechanisms underlying NK cell tolerance induction in a murine prenatal transplantation model.

Main Methods:

• Utilized a murine prenatal transplantation model to generate mixed hematopoietic chimeras.
• Analyzed NK cell repertoire formation, licensing, and receptor expression in response to prenatal alloantigen exposure.

Main Results:

• Prenatal tolerance is established through the elimination of NK cells expressing allospecific activating receptors without corresponding inhibitory receptors.
• The critical checkpoint for NK cell tolerance occurs centrally in the bone marrow during late maturation, driven by activating receptor recognition of allogeneic ligand.
• Residual NK cells lacking inhibitory receptors exhibit an anergic phenotype but can upregulate inhibitory receptor expression peripherally, though this capacity is lost in mature chimeras.

Conclusions:

• Developmental allorecognition via activating receptors is crucial for establishing durable NK cell tolerance.
• This study proposes a new paradigm for understanding prenatal NK cell-alloantigen education, emphasizing the central role of activating receptors in tolerance induction.